1. Technical Field
The invention to a device and a method for optically scanning a machine-readable label applied to an object.
2. Discussion
Such devices and methods are employed, for example, at the check out lanes of a self-service store to read the objects selected by a customer. The objects to be scanned are items. Checking the items out is supposed to take place automatically so that the presence of a check out person is not needed. The label is, for example, a bar code. One or more scanning devices are arranged on a conveyor device in order to read the label on the product. Care must be taken that the items are brought individually to the scanning device and that the label is read by the scanning device when the object with the side showing the label is lying on the belt. The latter is particularly important since most items have labels in only one place and there is a possibility that the customer places the items on the belt with the side having the label downward. Items placed in this position cannot be read by a scanning device which is positioned above or to the side of the belts. If an item cannot be checked out, it is returned to the customer and the customer is required to place the item one more time in a different position on the belt. This results in a delay when checking the items out.
From the prior art DE 101 41 429 C1 a device is known for optically scanning labels in which a scanning device is located in a space between two belts. The scanning device allows a label on the underside of an item facing the belts to be read. The scanning device is part of a hollow body. To ensure that even very small objects pass from one belt to the other or arrive at a receiving tray, the gap and the scanning device positioned in the space are kept very narrow. In a second embodiment, the transparent hollow body is in the shape of a cylinder, the axis of which is aligned parallel to the return pulleys of the belts und which rotates at a speed synchronized to the speed of the belts. The disadvantage is that the scanning device involves a cost-intensive special installation because of the requirements mentioned and the transportation and identification of small objects cannot be guaranteed.